Cookies from months or even years ago can affect your browsing experience and privacy.

You will lose passwords and plugin preferences (if you use any), but with the new Safari Keychain functionality, that's less of an issue.

While looking for a particular kitchen sink which I knew existed, I inadvertently clicked on Amazon for a search for the sink. Did not find it that day on Amazon or anywhere else, but about a month later, I got an email from Amazon with the exact sink I had been looking for.

I agree, sort of creepy.

If I can't find a book, out of print or rare or whatever, I put it on my wish list. About half the time a copy will pop up in a few weeks. Totally creepy but we think maybe booksellers have access to wish lists in a generic way so they don't have to list everything in their stock at all times, but can browse the list and see someone want that turkey of an item that's been gather dust on their shelves for decades. I have no idea if that's how it really works, but at least it's a rational explanation so it doesn't feel entirely invasive.

Maybe?

I use ixquick for searches, and I believe there are other search engines that don't compile and sell personal data. Also I use firefox and have a ghostery plugin for it which eliminates a lot of the tracking cookies. I guess its enough to do the trick because Amazon knows what I search for on their site and offer suggestions based on that but they never bother me with outside searches.

wait for the Details to pop up under the Remove all website data.

Highlight the Google ones and any other that are not sites you know and press the delete button.

Do not delete the Democratic Underground one.You will have to relogin again if you do.

Yes, they do know what you're looking for. As you visited those other sites and did searches, trackers were placed in your browser. When you went to Amazon, it read them and knew what you'd been searching. Ghostery will block most of them.